I got something very similar about a month ago:

Success! You're registered. Get ready to earn your new-member exclusive bonus. Stay between May 1 and August 31, 2014, to earn:

• One Free Night Award when your first stay is complete.
• A second Free Night Award when your second stay is complete.

That's two Free Night Awards redeemable at any of our Category 1–6 hotels or resorts through December 31, 2014. Now all you have to decide is, where to?